Compressor



Jan. 19, 1954 M. R. A. CHABAY 2,666,571

COMPRESSOR Filed July 22, 1948 '5 Sheets-Sheet 1 COMPRESSOR 5 Sheets-Sheet 2 Filed July 22. 1948 W i i i g? Q n; w; h h h h m 22 6? i I l 9 z I L nfl l/ldrF/l/l/ w .i 1i a a 1954 'M. R. A. CHABAY 2,666,571

COMPRESSOR Filed July 22, 1948 5 Sheets-Sheet a COMPRESSOR 5 Sheets-Sheet 4 Filed July 22, 1948 Jan. 19,1954 M. R. A. CHABAY f 2,666,571

' COMPRESSOR Filed July 22.- 1948 s Sheets- Sheet 5 i Patented Jan. 19, 1954 UNITED STATES? PATENT OFFICE COMPRESSOR.

Marcel.Ren=Armand.Chabay, Paris, France, as-

signor to Societe dlhventions Aeronautiques eti Mecaniques S. I'. A. M., Geneva, Switzerland, a corporation ofswitzerland Application-July; 22;.1948, Serial No'. 40,031

Claims priority, application FranceJuly 28, 1947 2.Glaims.-. (Cl. 230-182) The present invention relates to improvement in multiple stage piston compressors, and is characterised in particular by the fact that the various cylinders, and also the accumulation chambers or reservoirs for the gas compressed-inthe cylinders other than the high pressure cylinder, are provided in asingle cylinder block provided with cooling fins suitably arranged at its periphery.

An extremely strong-and compactmulti-stage compressor isthus obtained. The arrangement"- of' the reservoirs, which are used-for storing the air compressed in the low and-intermediate pres sure cylinders in the cylinder block itself, eliminates the pipes which connected said cylinders to the variousreservoirs and thereby avoids the:

leaks which occurred at the jcintsof suchpipes. The invention also covers othercharacteristic arrangements which-may be used separately'orinany combinations, in particular: 7

l. The accumulation chambers or reservoirsfor the gas compressed in the low and-intermediate pressure cylinders are located in the cylinder block at the periphery thereof and near the base of the cylinders so that the walls of said chambers are perfectly cooledand; are

not subjected to the rise of temperature caused by the compression of the gas insaidcylinders;

2; The passages connecting said accumulation reservoirs or chambers. to the various. cylinders are provided in the walls of the cylinder: block. and of the cylinder head of the compressor.

3. The suction and delivery valvesv of' the:

' thebearings for the crankshaft are provided, is-

same, the compression strokes of the pistons are suitably distributed over. each revolutionofsaid crankshaft.

6. In the particular case of a three-stage-ccmpressor, the compression stroke inthe; low-- pressure cylinder takes place during; the suction strokes in the high and.internriediate, pressure cylinders, and conversely, the;compr.ession. strokes;

these latter cylinders take place during the suction stroke in the low-pressure cylinder.

7-. The volume of the various accumulation reservoirs or chambers: for the gas compressed inithe low and intermediate'pressure cylinders is a high multiple of the volume af the respective cylinder capacities filledfrom said chambers in order. to preventthegas from expanding in said chambers when the corresponding cylinders are being filled.

8; The crankcase of the compressor, in which integralwith the cylinder block.

9.,The cylinders. of the compressor are provided with liners which are forced into suitable bores in the cylinder block. and held axially in position by flanges, on the upper face of which is pressed the readily removable cylinder head of the compressor.

10. The cooling of. the. cylinder block and of the cylinder head, which are both provided with suitable fins, may be effected by a forced air circulation inside a. suitable hood surrounding these members.

11. This circulation of cooling air may be produced: by a fan, by an air-blast supplied with compressed air obtained. from the delivery ofthe compressonby a. suitably orientated air inlet arranged in the direction of the relative wind:

when said compressor. is mounted on. a vehicle, or by a combination of these. means.

The invention will be more clearly understood by means of theensuing description, made with reference to'the accompanying drawing which is only given by way of example and in which:

Fig. 1 is a longitudinal section of the com pressor taken along the line II of Fig. 2, the pistons being assumed to be near the end-of their. compression stroke for the low-pressure piston and near the end of their. suction stroke for the intermediate and high pressure pistons.

Fig. 2 is a transverse section taken along the line II-II of Fig. 1.

Fig. 3 is. a transverse section taken along the line III-III of Fig. 1.

Fig. 4 isa horizontal secticntaken through the line IVIV of Fig. 1.

Fig. 5 15a horizontal-section taken through the line V-V of Figs. 1 2 andv 3, showing more especially-th low and'intermediate pressure accumulation chambers, the openings of the passages leading. to the upper part of said chambers beingashown. in. dot-and-dash lines, while the pistons are assumed to have been removed;

Fig; 6 is a-fragmentaryview-of an embodiment of a compressor with a forced circulation of the cooling air.

Fig. l is a fragmentary section on a larger scale taken through the line VII-VII of Fig. 6.

Fig. 8 is a transverse section of the cowling taken along the line VIII-VIII of Figs. 6 and '7.

The three-stage compressor, which is illustrated by way of example in the drawings, comprises a cylinder block i in which are provided two bores with parallel axes. lhe bore 2 of smaller diameter is provided with a cylinderical liner 3 which is forced into it and which forms the wall of the high-pressure cylinder 4. The bore 4a. is provided with a liner which is forced into it and which is internally bored in such a manner as to form two superposed cylinders of different diameters ii and S which respectively determine the low and intermediate pressure cylinders 5a and i, as will be explained hereinafter (see in particular Figs. 1 and 3).

The cylinder block I is provided, over its entire periphery, with cooling fins as which are suitably arranged and calculated to effect a good heat exchange between the cylinder block i and the surrounding air. Said cylinder block I may, for example, be made of an aluminum alloy, the liners 3 and GE) forming the walls of the various cylinders being of cast-iron or of steel so as to offer great resistance to wear.

The cylinder block i is extended at its lower part by a crankcase 8 containing cylindrical bearings Q and iii, the of which is at right angles to the axes of the cylinders and is contained in the same plane. Said bearings 9 and iii are provided with bushings i i and 2 in which is journalled the crankshaft it of the compressor. Said shaft I3 is provided with two crank-pins Hi and it which are set at 186 to one another and are respectively located opposite the high-pressure cylinder on the one hand, and the intermediate and low pressure cylinders on the other hand.

On the crank-pin it is journalled an eccentri collar it provided with an arm IT which is pivoted on a pin i3 mounted in the forked end of a cylindrical piston 59 inserted with a running it in the bore of the liner 3 which forms the highpressure cylinder. Said piston i9 is provided with Iifiumber of circular grooves 20 intended to facilitate the lubrication of the contacting surfaces. it is obvious that said piston is could also be provided with fluid-tight devices such as piston-rings.

On the crank-pin lb of the crankshaft is journalled the bottom end of a connecting rod 22, the top end of whic is pivoted on a pin 2| mounted in bearings provided on the skirt of a differential piston. Said differential piston has two super-- posed skirts 2-3 and 2d of different diameters respectively corresponding to the diameters of the bores 5 and '6 provided in the liner ib. Circular grooves 25, which may house fluid-tight devices such as piston-rings, are provided at the periphery of the skirts 23 and 2d of the diiferential piston. As hereinbefore mentioned, the low-pressure cylinder E5 is formed by the upper end of the core to of the liner as. whereas the intermediate-pres sure cylinder l is formed by the annular space between the surface of the bore 5 of the liner 19 and the skirt as of the differential piston.

According to an important feature of the present invention and in order to obtain as uniform a distribution as possible of the mechanical energy over the crankshaft i3 during the rotation thereof, the setting of the crank-pins is and i5 and the arrangement of the cylinders and the pistons have been so provided that the compression stroke in the low-pressure cylinder 5a takes place during the suction stroke in the intermediate and high pressure cylinders, while the compression stroke in these latter cylinders takes place at the same time as the suction stroke in the low-pressure cylinder 5. Furthermore, the useful volumes of the low, intermediate and high pressure cylinders have preferably been chosen so as to correspond to the same initial volume of gas sucked in, taking into account the pressures obtained in these various cylinders at the end of the compression stroke.

One of the ends of the crankshaft [3 of the compressor is adapted to receive a suitable coupling device (not shown) connecting said crankshaft to the driving shaft. Thus the end of said crankshaft may be bored and provided with internal longitudinal splines 21 (Fig. 1)

In order to enable the various members of the compressor to be mounted and removed easily, the lower part of the crankcase ii is provided with openings 28 which are closed by covers held in position by any suitable means such as screws, studs or the like (not shown) On the trued upper face of the cylinder block i is fixed; by means of screws or studs so for example, a cylinder head 31 which is also provided with cooling fins 32. According to a characteristic arrangement of the present invention, the delivery and suction valves of the high and low pressure cylinders, and which will now be described in greater detail, are mounted in said cylinder head 3 i Opposite the upper end of the low-pressure cylinder (see Fig. 1), the cylinder head 3! is provided with a cylindrical opening 33, in the lower part of which is screwed a bushing es forming a seat for the suction valve 35 of the low-pressure cylinder 5a. Said bushing Ed is provided with a coaxial inner sleeve 36 which acts as a guide for the stem 31 of the valve 35 and which is connected to the bushing 3 by fins or ribs 38. A suitably calibrated spring 39 which is coaxial to the stem S'i bears, on the one hand against the upper end of the sleeve 355, and on the other hand against a washer 37a fixed on the stem 3? of the valve so as normally to hold said valve against its seat. In the screw-threaded upper portion of the opening 33 is screwed either an air inlet sleeve 35a provided with one or more filters as shown, or a pipe connected to the delivery end of a supercharger or like machine in the case in which the improved three-stage compressor according to the invention operates with a forced feed.

Opposite the upper end of the low-pressure cylinder 5 and diametrically opposite the open ing 33, the cylinder head (if has on its lower face a blind opening which leads to a chamber 2-2 provided in said cylinder head 3!. In the screwthreaded lower end of said opening is screwed a bushing 43 forming a seat for the delivery valve M of the 1ow-pressure cylinder so. Said valve M is normally held against its seat by means of a suitably calibrated spring it which is adapted to bear, on the one hand against the bottom of a blind hole provided in the stem of said valve, and on the other hand against the bottom of a blind bushing s? which is centred and held in position in the chamber in by means of ribs es. Said chamber d2, which is crescent-shaped (see Fig. 4) is connected, through a conduit t; provided in the cylinder head M, to a conduit 5i (Fig. 5) which in principle is parallel to the axes of the cylinders. Said conduit 5i opens at its lower end into a-.chamber.- 52i- (Fig.3): provided in'itheslowen'.

be explained?hereinaften Saidrchamber: 52 (see Figs; 1; 3-:and5 is connectedithrcugha passage: 53 th a radial hole .i i provided inthe wall: of the.- cylinder; blocki opposite the liner. of the-=-inter-'= mediate-pressure cylinder. In. saidi hole. 54 is: mounted a: valve-box 56' which can be easily: rea d' by means of a blind" cylindrical nut contains-awa'lve fiq which'forms the in t vaive of the intermediate pressure "cyl inder 'i which isnormally held against itsseat' by a suitably calibrated spring-5iii1ev When the valve hi'islifted-oiT-its seat; it"thusmlacesthe chamber 52, called low-pressure chamber, 1m communication with the inside of the intermediate-pressure cylinder? through-:anopening 58 provided in the-liner-4b opposite the=valve 51% In the liner 4b and opposite the opening 58 is providedan opening-fi9=whioli opensoppesite" theseat ofa valve-box -6 B"'-=w-hi'ch=is mounted; insuch a manner as to be readily removable bymeans of a screw 61'', inaradial hole 62 mm Vided in the'cylinder block I. 60' contains a valve 63; called intermediate pres-' sure delivery valve, whichisnormally.heldiagainst: its'seatby asuitably calibrated spring. 6d; The: insidecf'the valve-box fiii -isiconnected to apase sage ESE-which opensintoa chamber 65; called; intermediate-pressure chamber providedi in. the lower part ofthe cylinder block l(see Figs; 3iand. 4) Said" intermediat'e pressure chamber. 5.6. is connected, throughapassage.fil prcvided in the. cylinder block I parallel-totheaxes of.- the. cylinders, to a passage. 58 provided in the cylinder, head 3! of the compressor.

Saidcylihderhead 8'i.is:pr-ovided; opposite the uppere-nd of the higlrpressure cylinder, with a recess- 6%?- in which is. mounted. a valve-box TD; held in position by a blind nut. H; which-screws on its screw-threadedrupper.end. The valveiebox;v Hi is provided with-two: holes 72 ande'lfi; theaxes of which areparallel: to. the. axis; of: the highpressure cylinder. 42 The hole His connectedi througharadialhole 5 (see' Fig; 2-). tothe pas.- sage 58' providedin the cylinder head 31. The. lower. part of. the. chamber. 5'2v is chamfered so as to. form-a seat for-.theintake'valve'ifi, the1stem-. "of which isfisuitably guided; Said valvez'n'fi is. normally pressedagainstits seat:by;a1.spring i3; which .is adapted .to. bear, on the one handlagainst the valve-box, and on: the. otherqhand against a". washer i9 fixed on the stem 1! oftsaid valve.

Thesecond hole. TSLoi thevalve boxi's terminated by a conical bearing surface forming a seat for a delivery valve 84' which is held against :this seat by a spring 82: which ishoused in a blind axial cavity of said valve andis adapted to, bear. against the bottom of a blind guide bush 83.; The chamber 13' isconnected, through'a radial'hole 85 providedin the wall'of the valve-boxli3 to a delivery nozzle 86 provided on the cylinder. head 3!.

It will be seen that the locationand the methodof mounting used according to. the invention for. the intake and'delivery valvesofjthe varioustcyl inders of the compressor,. enable thesevar-ious valves to be adjusted and removed easily.

According to a feature of the invention and as hereinbefore described, it can be seen that the accumulation chambers or reservoirs 52 and 66 for the gaseous fluid compressed in the low and intermediate pressure cylinders are provided in the cylinder block I itself and at the part of same corresponding to the base of the cylinders,

Said valve box La. atzthazpointzwhere: the temperature-is ilcwest sincezthee heat: produced. by the. compression: of: thagaseoua-fihid :inxsaichcylinders-v isievacuatediin'. principle at the upper part: of? said: cylinders:-

- Furthermore, said accumulation chambers or reservoirs: 52 and 6,6 are perfectly cooled by the fins 265 provided. on: the cylinder block. i:

The operation of: the. three stag e: compressor hereirrbefore described is easy t'o understand and will! now; be described. The crankshaft t3 and thevarious pistons-zbeing assumed to occupy the positionsshown inithe drawing; when said cranh shaft rotates, thelow; and intermediate pressuredifferential piston movesdownwards and a certain vacuum is created in the upper partof the low-pressure-' cylinder 5522. The valve --35 lifts off it's seat -and the gaseousfiiiid penetratesiintothe' cylinder 5w throughout the -whole of the suction stroke of the low pressurepiston; through the fiit'er-orfilt'ersdt andthe sleeve sea. Attire-end" of this suction stroke; thevalve 35* is closed by the ac ion of the-spring 39; When the'differen tial piston moves upwards, the-gas sucked-into the cylinden 5 is= compressed and' when its pressure=exceeds that corresponding to the calibrationof the'springx ifi of thelow pressure delivery, valve-4 3'; saidvalve 3 i lifts and thegas compressedat low pressure in the cylindcrea isforced through thechambertfiiand thepassagesie and '5 i into the low-pressure accumulation chamber or reservoir iiii where it" is cooled by; the contact of 'thecold walls of said chamber.

During-the up-stroke-of the difi'erential piston corresponding to the compression stroke in the low pressure -cylinder 5a; a' vacuum is" created" in the" intermediate-pressure cylinder 1, the intermediate-pressure inlet" valve 57 is. lifted. ofi its seata'gainst the'action of the=calibrated spring;

58c: and thegas which is compressed at low pressure and-storedin thechamber 5 2'penetrates into; the intermediate-pressure cylinder 7. When the; differential piston reaches its extreme high;

position, the intermediate pressureinlet valve 5'1' closes. i/Vhen'saiddifierential piston moves downwards (suction stroke in the low-pressure cylinder) the low-pressure gas contained in' the interme'diate pressure cylinder 71 is compressed and when its pressureexceeds that correspond ing to the calibration of-tl1espring 84 of the" int'ermediate -pressure delivery valve- 6-3, said valve 63 islifted" off its seat" and the gascompressed at intermediate=pressure inthe cylinder 'lis forced-through the opening 59; the valveboxtfiwand, the passage-Edinto the intermediatepressure accumulation chamber or reservoir" 65 where itiscooled by contact with thecold wallsof said chamber;

At" thebeginning: of the down-stroke of the high-pressure piston I 9-; which takes placewhen the differential piston-moves upwards (compression' stroke-in the low-pressure I cylinder and suc tion stroke inthe= intermediate--pressure cylin-- der), the' high pressure inlet valve- W islifted 01f" its seat and the compressed gas at intermediate. pressure contained in the intermediate pressure chamber-6t penetrates into the cylinder 4' through the passages 6-7 and $33- the=- opening 15, the" chamber T2- and theopening uncovered by" the; valve 76 At the end of the suctionstroke ofthe high pressurepiston IS; the valve 16 is closed by the action of the calibrated spring 18. When the piston !9 moves upwards, the gas at intermediate pressure contained in the cylinder 4 is compressed and when its pressure exceeds that corresponding to the calibration of the spring 82 of the high-pressure delivery valve 8|, said valve 8| lifts and the gas compressed at high pressure in the cylinder 4 is forced through the chamber 13 into the delivery nozzle 85 of the compressor.

According to the invention and in order to prevent the pressure of the gas contained respectively in the low and intermediate pressure accumulation chambers or reservoirs 52 and 65 from falling considerably during the filling of the intermediate-pressure and high-pressure cylinders and i, the volume of said accumulation chambers or reservoirs is chosen equal to a high multiple of the respective cylinders to be filled.

According to the invention, the lubrication of the various members is forced. The lubricant is forced through a pipe (not shown) into a chamber provided in the crankcase wherein said lubricant is conveyed in the known manner and through suitable ducts 38 either directly to various members to be lubricated (bearings, connesting-rod big end, eccentric), or by projection on to certain other members (cylinders, pistons, connecting-rod small end, etc.).

In order to provide a more efficient cooling of the cylinder block 5, a forced air circulation may be produced on the fins 26 of the cylinder blocl; i and also on the fins 32 of the cylinder head 3!. For this purpose, and in an embodiment which appears to be advantageous at the present moment, a cowling 89 of sheet metal for example, is arranged round the compressor, as is best shown in Figs. 6 to 8 of the drawings. Said cowling 83 is eccentric with respect to the cylinder block 1 in such a manner that at one point it is tangential to the periphery of the fins 26 and to a transverse fin a. The cooling air is admitted under said cowling on one side of this tangential portion, on to the fins. The outlet of the air is effected on the opposite side to its inlet, through an opening 90 provided in the cowling in such a manner that said air is con strained to flow over the entire surface of the fins 26 and 32 of the cylinder block and head I and 3! respectively, thereby effecting a perfect cooling of the compressor.

The cooling air may be forced for example by a centrifugal fan 81 mounted on the end of the crankshaft it of the compressor. A suitable case 92, integral with the cowling 89 of the compressor and surrounding the blades 9! of the fan, conveys the air forced in to the suitable point of the cowling 89 as hereinbefore mentioned. Instead of using a fan, it would also be possible, when the compressor is mounted on a vehicle, to arrange an air intake in the direction of the relative wind and thereby obtain a flow of cooling air inside the cowling 39. It is also possible, as shown in Fig. 7 of the drawings, to comibine both of these means, the fan being supplied with the air conveyed through a pipe 92 leading to the intake located in the relative wind. The opening of the supply pipe 83 of the lowpressure cylinder of the compressor may be located inside said pipe t2 so as to provide a slight supercharging of said compressor.

It is obvious that the invention is not limited to the embodiments hereinbefore described and illustrated by way of example, but extends to all embodiments involving the use of the features hereinbefore set forth and fulfilling the desired requirements. Thus, in particular, the compressor according to the invention could be a twostage compressor by eliminating either the highpressure cylinder and piston, or the intermediate-pressure cylinder and piston and their associated members, or again, said compressor could be a four-stage compressor by replacing the high-pressure cylinder and piston by a double cylinder and a differential piston of the type of those hereinbefore described by the name of low and intermediate pressure cylinders and pistons. Instead of being parallel to oneanother, the axes of the cylinders could be inclined (V-type arrangement) or be in alignment (so-called flat type).

I claim:

1. A three stage piston type compressor comprising a single cylinder block with two bores therein, said bores having parallel axes, a first piston slideable in one bore, which constitutes the high pressure cylinder of said compressor, a diiferentiai piston having mounted thereon two superposed skirts of different diameters, the top skirt being of a larger diameter than the bottom skirt, and slideable in the other bore having therein a liner with stepped diameters to receive said skirts, the portion of the bore above the top skirt constituting the low pressure cylinder of the compressor and the portion of the bore between the outer surface of the lower skirt and the inner surface of the liner having a diameter sufficient to receive the top skirt constituting the intermediate pressure cylinder, a single driven crankshaft and means connecting each of said pistons to said crankshaft whereby the compression stroke in the low pressure cylinder takes place during the suction stroke in the intermediate and high pressure cylinders, while the compression stroke in these latter cylinders takes place at the same time as the suction stroke in the low pressure cylinder.

2. A compressor according to claim 1, comprising inside of said cylinder-block, near its perip iery and in the vicinity of the lower part of said bores, around said bores, two accumulation, passage and cooling chambers for the compressed gas, the one, for low pressure, receiving the compressed gas coming from the low pressure cylinder and feeding the intermediate pressure cylinder, the other, for the intermediate pressure, receiving the compressed gas coming from the intermediate pressure cylinder and feeding the high pressure cylinder.

MARCEL RENE ARMAND CHABAY.

Maniscalco July 9, 

